The invention relates to methods for improving the mobility and production rate of a viscous crude oil by forming an oil-in-water emulsion with blends of certain surfactants.
The pumping of viscous crude oils from production wells and subsequent pipeline transport is difficult because of the low mobility of the oil. Prior methods for overcoming this problem included addition of lighter hydrocarbons, such as kerosene or light condensate, and heating the crude oil. These prior art methods are expensive and wasteful of energy.
Still another method of reducing the viscosity of heavy crude oils is by means of an oil-in-water emulsion. The following patents disclose such methods using a variety of agents to form emulsions for this purpose:
U.S. Pat. No. 3,380,531; PA1 U.S. Pat. No. 3,467,195; PA1 U.S. Pat. No. 4,108,193; PA1 U.S. Pat. No. 4,152,290; PA1 U.S. Pat. No. 4,153,573; PA1 U.S. Pat. No. 4,153,575; PA1 U.S. Pat. No. 4,162,989; PA1 U.S. Pat. No. 4,192,767 and PA1 U.S. Pat. No. 4,214,999. PA1 Ar is octylphenyl or nonylphenyl, PA1 n is a number from 2 to 10, PA1 p is a number from 10 to 100, PA1 a is a number from 10 to 40, PA1 b is a number from 15 to 55, PA1 c is a number from 10 to 40, PA1 R.sup.1 is C.sub.8 to C.sub.18 alkyl and PA1 R.sup.2 is C.sub.12 to C.sub.18 alkyl. PA1 (A.sup.1) The sodium or ammonium salt of 4-C.sub.9 H.sub.19 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.4 OSO.sub.3 H and PA1 (B) 4-C.sub.8 H.sub.17 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.70 OH; PA1 (A.sup.1) The sodium or ammonium salt of 4-C.sub.9 H.sub.19 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.4 OSO.sub.3 H and PA1 (B) 4-C.sub.8 H.sub.17 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.30 OH; PA1 (A.sup.1) The sodium or ammonium salt of 4-C.sub.9 H.sub.19 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.4 OSO.sub.3 H and PA1 (C) ##STR5## having an HLB of 16; 4. PA1 (A.sup.1) The sodium or ammonium salt of 4-C.sub.9 H.sub.19 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.4 OSO.sub.3 H and PA1 (B) 4-C.sub.9 H.sub.19 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.100 OH; PA1 (A.sup.1) The sodium or ammonium salt of 4-C.sub.9 H.sub.19 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.4 OSO.sub.3 H and PA1 (B) 4-C.sub.8 H.sub.17 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.10 OH; PA1 (A.sup.3) The sodium or ammonium salt of the amphoteric surfactant ##STR6## where R.sup.2 is C.sub.12 to C.sub.18 alkyl and (B) 4-C.sub.8 H.sub.17 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.30 OH; PA1 (A.sup.2) The disodium salt of ##STR7## where R.sup.1 is C.sub.8 to C.sub.18 alkyl and (B) 4-C.sub.9 H.sub.19 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.100 OH; PA1 (A.sup.1) The sodium or ammonium salt of 4-C.sub.9 H.sub.19 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.4 OSO.sub.3 H and 4-C.sub.9 H.sub.19 C.sub.6 H.sub.4 (OCH.sub.2 CH.sub.2).sub.30 OH.
However, each of these methods has serious drawbacks in that, for example, the resulting emulsion is still relatively viscous, they require heating to give an emulsion of sufficiently low viscosty, or subsequent separation of oil is difficult.
U.S. Pat. No. 4,239,052 discloses the use of a combination of an ethoxylated alkylphenol and a low molecular weight alkylaryl sulfonate to reduce the viscosity of viscous hydrocarbons. U.S. Pat. No. 4,246,919 discloses a method employing a combination of an ethoxylated alkylphenol and an ethoxylated polypropylene glycol. U.S. Pat. No. 4,249,554 discloses an emulsion from using a combination of an ethoxylated alkylphenol and a salt of an ethoxylated alcohol sulfate. U.S. Pat. No. 4,265,264 relates to a method employing a combination of a salt of an ethoxylated alcohol sulfate and certain polyoxyethylene polyoxypropylene copolymers or an ethoxylated alcohol. U.S. Pat. No. 4,285,356 discloses a method for reducing the viscosity of viscous hydrocarbons by forming an emulsion with a combination of certain alkylpolyether ethoxylated sulfates and an alcohol ether sulfate.